Fault Conditions

Brake Light Switch Circuit. Open / Short to B+







Fault symptoms
- CHECK ENGINE.
- Cruise control not working.

On-Board Diagnostics
Type of diagnosis:
- Continuous. But interrupted when fault criteria fulfilled and will not restart until next driving cycle.

Enable criteria:
- Engine running. Vehicle speed has dropped from 40 km/h to 3 km/h in 2 to 12 s on 5 occasions.

Fault criteria:
- Continuous battery voltage on control module input.

Dependents:
- None.

System reaction to a fault:
- Cruise control blocked.

OK report:
- Brake pedal depressed and then released on one occasion.

Fault handling: Fault Handling III, Other Emission-Related Component & Function
- Type III.

Diagnostic help
Fault diagnosis concerns an electrical fault in the connecting leads.
Functions in the diagnostic tool related to the fault:
- Diagnostic status for the diagnosis.
- Brake light, unit ON/OFF.

For information, Tech 2 Menu Structure, DTC Menu, Read Value, Activate, Sys Info

Checking the wiring
Jiggle the wiring harness at several points and in different directions to detect intermittent breaks and short circuits. Observe the multimeter, diagnostic tool or test lamp during the check.

Proceed to Diagnostic Procedures Checking Brake-Lights Functionality